As a method of forming a protection film for a medium such as a hard disk, there is a CVD (Chemical Vapor Deposition) method using a reactive gas such as acetylene (C2H2) or ethylene (C2H4). Recently, a thinner protection film of carbon or the like (carbon protection film) formed on a magnetic recording layer is required to further shorten the head flying height and the spacing distance between a magnetic read head and the magnetic recording layer of a medium, and improve the drive characteristic.
On the other hand, the limitation of the thickness of the carbon protection film formed by CVD is said to be 2 to 3 nm owing to its characteristic. As a technique replacing CVD, attention has been paid to a deposition method (vacuum arc deposition) which uses an arc discharge and can form a thinner carbon protection film (see PTL 1 and PTL 2). Vacuum arc deposition can form a harder carbon protection film with a lower hydrogen content in comparison with CVD, and has the possibility of decreasing the film thickness to about 1 nm.
In the vacuum arc deposition disclosed in PTL 1, carbon ions required for a ta-C film are generated by setting a target made of graphite as the cathode, and generating an arc discharge between the target and the anode arranged near the target. The arc discharge is generated by bringing a striker connected to the anode closer to or into contact with the target.
In such vacuum arc deposition, an arc discharge is generally generated by using a columnar target and bringing a striker into contact with the vicinity of the center portion of the upper surface of the target. A position with which the upper surface of the target has come into contact (a position where the arc discharge has been generated) is shaved to be a dent (arc spot). Therefore, unevenness of the target caused by the arc spot is averaged by rotating the target to change the contact position with the striker. Note that when the columnar target is used, a deposition rate varies if an arc spot is generated in the peripheral portion of the upper surface of the target. It is therefore preferable that the arc spot is generated only in the center portion of the upper surface of the target. However, the peripheral portion of the upper surface of the target remains without being shaved unless the arc spot is generated in the peripheral portion of the upper surface of the target. To cope with this, PTL 2 has proposed a technique of planarizing the upper surface of a target by shaving it with a grinder or the like when an arc spot (dent) on the upper surface of the target becomes large to some extent.